It’s the silly season of attention-getting campaign ads, and Hollywood director, producer and political activistRobert Greenwald – of “Outfoxed” fame — may have hit the sweet spot with his spoof ad on Prop. 17, the coming insurance ballot initiative backed largely by Mercury General Insurance.

With Mercury and the “Yes on Prop. 17″ forces ready to drop some big cash on expensive TV ad time to argue the measure will increase competition and reduce consumer costs on insurance, this scathing spot from Greenwald’s progressive Brave New Films — which has produced such documentary efforts as “Outfoxed: Rupert Murdoch’s War on Journalism,” “Sick for Profit,” “WalMart: The High Cost of Low Price,” and “Iraq for Sale” –aims to counter.

It stars a “Mercury spokesman” haplessly trying to convince folks that insurance companies really do want to spend millions to be, uh, good guys and cut premium costs. (The sounds of hysterical laughter are a hallmark of this spot.) The classic Greenwald effort looks timed to take some of the punch out of that coming Mercury campaign.

The spot is a production of StopProp17.org, the consumer group fighting the initiative.

With big money backing the measure — Mercury has already put $3.5 million into the kitty — voters will be deluged with information on Prop. 17, which will be on the June primary ballot. So here’s the first salvo in a war that’s only just beginning.